1. Field of the Invention
This invention relates to determining the condition of a gold surface by means of optical reflection.
2. Description of the Prior Art
In the gold electroplating art, a typical quality control check is a visual inspection of a gold plated article for discolored or "burnt" deposits, known as "brown gold". With the advent of continuous high-speed strip line gold plating apparatus, it has become desirable to automate the inspection of gold plated surfaces; see, for example, the plating apparatus described in U.S. Pat. No. 4,153,523 assigned to the same assignee as the present invention. In addition, the visual inspection of gold plated objects typically results in less than uniform results, with inspection by different persons resulting in slightly different levels of acceptability.
It is known that the degree of surface roughness of gold deposits affects the characteristics of the reflected light; see, for example, "Electrochemical And Structural Aspects of Gold Electrodeposition From Dilute Solutions By Direct Current", by H. Y. Cheh and R. Sard in Journal Of The Electrochemical Society, Vol. 118, pages 1737-1747, (1971). However, the prior art studies of specular reflectivity did not correlate very well with the surface conditions monitored by visual quality control checks.
It is therefore desirable to have an automated high-speed method of detecting surface imperfections on plated gold surfaces that gives an accurate and reliable indication of unacceptable surface conditions.